Marbles

I really suck with probability questions can someone help me out?

Each of two boxes contains 20 marbles, and each marble is either black or white. The total number of black marbles is different from the total number of white marbles. One marble is drawn at random from each box. The probability that both marbles are white is .21. What is the probability that both are black?

Each of two boxes contains 20 marbles, and each marble is either black or white. The total number of black marbles is different from the total number of white marbles. One marble is drawn at random from each box. The probability that both marbles are white is .21. What is the probability that both are black?

Let, be the amount of white and be the amount of black. We are told that . (And of course ).

The probability is .21 meaning the ratio of favorable outcomes to possible outcomes is this fraction. The number of favorable outcomes is . The number of possible outcomes is,
Thus,
More simply,
Thus,
Which is impossible for is an integer.
Your question is an impossibility.

Each of two boxes contains 20 marbles, and each marble is either black or white.
The total number of black marbles is different from the total number of white marbles. ?
One marble is drawn at random from each box.
The probability that both marbles are white is 0.21 ?
What is the probability that both are black?